Digital wideband architectures are a relatively recent invention and efficient digital delay synthesis circuits and architectures did not previously exist for wideband channelized architectures. Digital wideband architectures are useful for high speed digital communication technology. Herein, wideband may be used to refer to bandwidths from kilohertz (KHz) to multi-gigahertz (GHz) bandwidths. Channelized architectures become necessary when the bandwidth of the signals being considered are a multiple of the speed of digital logic. A direct digital synthesizer (DDS) is a type of frequency synthesizer used for creating arbitrary waveforms from a fixed-frequency reference clock. Thus, a direct-digital synthesizer (DDS) uses a digitally deterministic frequency synthesis technique, which is based on a digital definition of the result to generate a signal. A DDS uses logic and memory to digitally construct the output signal, and a data conversion device to convert it from the digital to the analog domain. Therefore, the DDS method of constructing a signal uses digital principles, and the precise amplitude, frequency, and phase may be known and controlled.
Previously analog voltage controlled oscillators were used to create waveforms, resulting in a limited frequency range. In digital architectures, the current practice involves direct digital synthesis (DDS) where multiple parallel DDS circuits create I/Q at very high rates directly for bandwidths at speeds that are multiples of the digital logic. In other methods, each technique, defined as a waveform with a specific instantiation of frequency, phase, and amplitude parameters as a function of time, had to be aware of the channelized structure explicitly switch channels in the architecture or have a specific parameter selecting a channel. Each technique typically had a DDS associated with it and raw I/Q data are passed around data lanes.
Channelized radio receivers divide an incoming radio frequency signal into plural frequency-segregated segments. Such receivers perform the channelizing function for a variety of reasons including the accomplishment of differing signal processing steps in the different channels, the physical separation of hardware relating to different channels, reduction of data rate per channel, and the preclusion of cross channel interference effects. However, a problem with channelization is that typically a frequency and a channel must be calculated and specified for each signal, which adds complexity, particularly when summing signals together.
Many attempts have been made at the wideband receive side of channelized architectures. There have also been architectures for the transmit side of narrow band radio waveforms, such as for communications. However, very little work has been shown for wideband channelized transmit architectures.